\subsection*{Packet Capturing}
\begin{frame}
\frametitle{Packet Capturing: Hardware View}
\begin{columns}
\column[t]{0.5\textwidth}
\vspace{-15em}
\begin{enumerate}
	\item \textbf{Receiving} network packets
		\begin{itemize}
			\item receive at network adapter
			\item DMA transfer in RAM \newline
		\end{itemize}
	\item \textbf{Filtering} the received packets 
		\begin{itemize}
			\item \emph{Berkeley Packet Filter}\newline
		\end{itemize}
	\item \textbf{Storing} to the hard disk
		\begin{itemize}
			\item using a system call
		\end{itemize}
\end{enumerate}
\column[t]{0.5\textwidth}
\includegraphics [width=0.82\textwidth, keepaspectratio]{pics/HardwareView}
\end{columns}
\end{frame}

\begin{frame}
\frametitle{FreeBSD Packet Capturing Stack}
\begin{itemize}
	\item \textbf{Network driver}
		\begin{itemize}
			\item Receiving packets\newline
		\end{itemize}
	\item \textbf{Berkley Packet Filter} (BPF)
		\begin{itemize}
			\item Filtering packets\newline
		\end{itemize}
	\item \textbf{User-space application}
		\begin{itemize}
			\item Accessing received packets
			\item Initiates:
				\begin{itemize}
					\item Storing packets to hard drive
					\item Output packets information to the terminal
				\end{itemize}
		\end{itemize}
\end{itemize}
\end{frame}

\subsection*{How does it work}
\begin{frame}
	\begin{center}
	\huge{How does standard packet capturing work}
	\end{center}
\end{frame}

\begin{frame}
\frametitle{FreeBSD Standard Packet Capturing Stack}
\begin{columns}
\column[t]{0.5\textwidth}
\vspace{0em}
\newline
\begin{itemize}
\item <6-> Access packets
\item <5-> Packet filtering
\item <4-> Interrupt Service Routine
\item <3-> Interrupt
\item <2-> DMA-Transfer
\item <1-> Packet is received and saved in Adapter-FIFO
\end{itemize}
\column[t]{0.5\textwidth}
\vspace{-2em}
\begin{figure}
	\only<1>{\includegraphics [height=55mm,width=60mm]{pics/3copy_0}}
	\only<2>{\includegraphics [height=55mm,width=60mm]{pics/3copy_0.5.eps}}
	\only<3>{\includegraphics [height=55mm,width=60mm]{pics/3copy_0.7.eps}}
	\only<4>{\includegraphics [height=55mm,width=60mm]{pics/3copy_1}}
	\only<5>{\includegraphics [height=55mm,width=60mm]{pics/3copy_2}}
	\only<6>{\includegraphics [height=55mm,width=60mm]{pics/3copy_3}}
\end{figure}
\end{columns}
\end{frame}


\input{section/Background/Disadvantages.tex}
